PIN ASSIGNMENTS
28-PIN DUAL-IN-L1NE PACKAGE AND 28-PIN SOIC PACKAGE
Voo
05Cl 05C2 TCAP/P07 TCMP P05
pco
PCl PC2 PC3 PC4 PC5 PC6 PC7
MOTOROLA MICROPROCESSOR DATA
II
MOTOROLA
8-Bit Microcontroller Unit
The MC68HCL05C4 (HCMOS) microcontroller unit (MCU) is a member of the M68HC05 Family of microcontrollers. This high-performance, low-power MCU has parallel 1/0 capability with pins pro-grammable as input or output. This publication contains condensed information on the MCU; for more detailed information, contact your local Motorola sales office.
The following block diagram for depicts the hardware features; additional features available on the MCU are as follows:
• Serial Communications Interface (SCI) System
• Serial Peripheral Interface (SPI) System
This document contains information on a new product SpeCifications and information herein are subject to change without notice.
MOTOROLA MICROPROCESSOR DATA 3-1012
Port C I/O Lines
SIGNAL DESCRIPTION
The signal descriptions of the MCU are discussed in the following paragraphs.
VOO ANO VSS
Power is supplied to the mlcrocontroller uSing these two pinS. VOO IS the positive supply, and VSS is ground.
IRQ
This pin IS a programmable option that provides two different choices of Interrupt triggering sensitivity. Refer to INTERRUPTS for more detail.
OSC1,OSC2
These pinS provide control input for an on-chip clock oscillator circuIt. A crystal, a ceramic resonator, a resistor capacitor combination, or an external signal connects to these pinS providing a system clock. A mask option se-lects either a crystal/ceramic resonator or a resistor/ca-pacitor as the frequency determining element. The osciliator frequency IS two times the Internal bus rate.
Crystal
2 MHz 4 MHz Units
RSMAX 400 75 Il
Co 5 7 pF
Cl 0008 0012 jtF
COSCl 15-40 15-30 pF
COSC2 15-30 15-25 pF
Rp 10 10 Mil
0 30 40 K
RC Oscillator
With this option, a resistor is connected to the OSCillator pins as shown In Figure 1 (d). The relationship between Rand fosc IS shown in Figure 2.
Crystal
The circuit shown In Figure 1 (b) IS recommended when using a crystal. USing an external CMOS OSCillator IS rec-ommended when crystals outside the specified ranges are to be used. The crystal and components should be mounted as close as possible to the Input pinS to mini-mize output distortion and start-up stabilization time. Re-fer to ELECTRICAL SPECIFICATIONS for VOO specifications.
Ceramic Resonator
A ceramic resonator may be used In place of the crystal In cost-sensitive applications. The circuit In Figure 1 (b) IS recommended when using a ceramic resonator. Figure 1 (a) lists the recommended capacitance and resistance
Ceramic Resonator 2-4 MHz Units
RS (tYPical) 10
n
Co 40 pF
C, 43 pF
COSC' 30 pF
COSC2 30 pF
Rp '·10
Mn
Q 1250 ~
(a) Crystal/ Ceramic Resonator Parameters
MCU
OSC, OSC2
39 Rp 38
o
COSC'l"
"J"
COSC2(b) Crystal/Ceramic Resonator OSCillator Connections
(d) RC OSCillator Connections
-3-8---~IDrl
~~ _______
3_9(C) EqUivalent Crystal Circuit
MCU OSCl
39
Unconnected
'---<
External Clock (e) External Clock Source ConnectIOns(For Crystal Mask Option Only) Figure 1. Oscillator Connections
MOTOROLA MICROPROCESSOR DATA 3.1013
II
II
Figure 2. Typical Frequency vs Resistance for RC Oscillator Option Only values. The manufacturer of the resonator considered
should be consulted for specific information on resonator operation.
External Clock
An external clock should be applied to the OSC1 input with the OSC2 input not connected, as shown in Figure 1(e). This option may only be used with the crystal os-cillator mask option.
INPUT CAPTURE (TCAP)
This pin controls the input capture feature for the on-chip programmable timer.
OUTPUT COMPARE (TCMP)
This pin provides an output for the output compare feature of the on-chip timer.
RESET
This pin is used to reset the MCU and provide an or-derly start-up procedure by pulling RESET low.
INPUT/OUTPUT PORTS (PAO-PA7, PBO-PB7, PCO-PC7) These 24 lines are arranged into three 8-bit ports (A, B, and C). These ports are programmable as either inputs or outputs under software control of the data direction registers. Refer to PROGRAMMING for additional infor-mation.
FIXED INPUT PORT (PDO-PDS, PD7)
These seven lines comprise port D, a fixed-input port.
All special functions that are enabled (SPI, SCI) affect thiS port. Refer to PROGRAMMING for additional information.
PROGRAMMING
Inputloutput port progrmming, fixed input port pro-gramming, and serial port programming are discussed in the following paragraphs.
INPUT/OUTPUT PORT PROGRAMMING
Any port pin IS programmable as either an input or an output under software control of the corresponding data direction register (DDR). Each port bit can be selected as output or input by writing the corresponding bit in the port DDR to a logic one for output and logic zero for input.
On reset, all DDRs are initialized to logic zero to put the ports in the input mode. The port output registers are not initialized on reset but may be written to before setting the DDR bits to avoid undefined levels.
When programmed as outputs, the latched output data is readable as input data regardless of the logic levels at the output pin due to output loading. The latched output data bit may always be written. Therefore, any write to a port writes all of its data bits, even though the port DDR is set to input. This port write may be used to initialize
FIXED INPUT PORT PROGRAMMING
Port D is a fixed input port (PDO-PD5, PD7) that monitors the external pins whenever the SCI or SPI is disabled.
After reset, all seven bits become valid inputs because all special function drivers are disabled. For example, with the SCI enabled, PD~ and PD1 inputs will read zero.